Emit callbacks

Emit callbacks are invoked when an instance of a registered class is
emitted by yaml_emit() or
yaml_emit_file(). The callback is passed the object to
be emitted. The callback must return an array having two keys:
"tag" and "data".
The value associated with the "tag" key must
be a string to be used as the YAML tag in the output. The value associated
with the "data" key will be encoded as YAML
and emitted in place of the intercepted object.

Ejemplo #1 Emit callback example

<?phpclass EmitExample { public $data; // data may be in any pecl/yaml suitable type